Our broad objective remains that of understanding the development of emotional expressions during infancy. Previous work emphasized the biological and naturalistic context of such expressions, while current work emphasizes their social context and makes increasing use of experimental studies. A biosocial view highlights that in human infancy, without language, emotional expressions are prominent and provide a medium for messages in the infant-caregiver system. Some messages are biologically necessary for the infant's survival, others guide exploration and learning. The first part of the proposal concerns studies of infant-to-mother signaling of emotion and the second part concerns mother-to-infant signaling. In Part I, studies analyze the various dimensions and discrete emotions which adults recognize in facial expressions of normal infants at different ages. Other studies contrast facial expressions of emotion produced by normals and infants born with Down's syndrome; these studies also compare the meaning of different emotional signals for care-giving actions. In addition, a cross-sectional survey of maternal perceptions of infant emotions from birth through 18 months will be supplemented with two longitudinal samples. Finally, other studies will investigate the adaptive significance of individual differences in maternal perceptions of infant emotional signals as they occur among normal mothers and among those at presumed risk for problems in parenting. Part II will use three experimental paradigms involving infant uncertainty in order to investigate mother-to-infant signaling of emotion. In these, mothers will signal a variety of emotional expressions (happiness, interest, anger, fear and a signal of unavailability--i.e., reading a magazine). Infants in the latter half of the first year will be studied as they make use of their mothers' emotional expressions for regulating their own affects and for coping with the uncertainty. In addition, a study will be done of infant reactions to adult emotional expressions in which facial expressions and vocalic expressions will be compared.